1. Field of the Invention
The present invention relates to a novel azo compound, and a pigment dispersant, a pigment composition and a pigment dispersion including the azo compound. The present invention also relates to a toner including an azo pigment and a novel azo compound.
2. Description of the Related Art
A fine pigment is likely to have a strong cohesive force between pigment particles in a medium such as an organic solvent or a melted resin. Therefore, color unevenness and a remarkable decrease in coloring power are brought about in drawdowns in some cases. A further problem that occurs is a decrease in gloss of colored surfaces and coated surfaces of drawdowns.
As a method of improving the pigment dispersibility, polymer dispersants having sites having high affinity for pigments and polymer sites to impart the dispersibility in media have conventionally been used.
As a polymeric pigment dispersant for a toner, an example is disclosed which uses a dispersant in which an azo or disazo chromophore containing a substitution product of acetoacetanilides is bonded to a polymer (see Japanese Patent No. 03984840). An example is disclosed which uses Solsperse® (made by Lubrizol Corp.) as a comb polymeric dispersant having an acid or basic site (see WO 99-42532).
On the other hand, an example is disclosed which uses a polymer dispersant as a dispersant of a pigment for inkjet recording in which polymer dispersant a chromophore having a lower molecular weight than 95% of the molecular weight of an azo pigment is bonded to a water-soluble polymer main chain (see U.S. Pat. No. 7,582,152).